Abstract: PURPOSE: To investigate the short-term and long-term effects of all-ceramic onlay on restoration of premolars and its influence on dental function. METHODS: Ninety-five premolars receiving root canal treatment in People's Hospital of Peking University from January 2017 to January 2018 were enrolled, and randomly divided into two groups based on different repairing methods. Patients in the control group (n=47) received full crown restoration, while patients in the experimental group(n=48) received all-ceramic onlay restoration. The success, survival and failure rates of the teeth were compared. The United States Public Health Service(USPHS) and occlusal function of the prosthesis were compared 6, 12 and 36 months after treatment. The data were processed using SPSS 19.0 software package. RESULTS: The success and survival rate of the experimental group were higher than those of the control group, but without significant difference (P>0.05). The morphology, marginal integrity, marginal coloration, surface texture, secondary caries, gingival health and proximal contacts showed no significant difference between the two groups 12 months after treatment(P>0.05). Thirty-six months after treatment, the marginal integrity, marginal coloration and surface texture showed no significant difference between the two groups (P>0.05), while the morphology, secondary caries, gingival health and proximal contacts were significantly better in the experimental group than in the control group (P<0.05). The occlusal function between the affected side and contralateral side of both groups showed no significant difference 6, 12 and 36 months after treatment(P>0.05). CONCLUSIONS: All-ceramic onlay restoration of premolars has high success and survival rate, and good short-term and long-term restoration effect, which is beneficial to improve the occlusal function of the affected teeth.

Key words: All-ceramic onlay, Premolar defect, Short term effect, Long term effect, Dental function